Schematic representing the role of stem and progenitor cells in vascular repair. Multiple stem and progenitor cells may contribute to vascular repair in vivo. Both embryonic stem cells (ESCs; blue) and induced pluripotent stem cells (iPSCs; orange) can be differentiated into vascular cells and may be utilised in vivo as endothelial cells with the potential to engraft into damaged or ischaemic host vasculature. Mesenchymal stem cells (MSCs; pink) have the potential to differentiate into mural cells such as pericytes and smooth muscle cells. This would be particularly useful in ischaemic tissue as mural cells are essential for stabilisation of newly formed vessels and communicate closely with endothelial cells through adherens junctions. The protein N-cadherin is depicted as pink diamonds. Multipotent adult progenitor cells (MAPCs purple) may also be differentiated into endothelial cells to aid vascular repair and reduce ischaemia. Early endothelial progenitor cells/myeloid angiogenic cells (eEPCs/MACs; red) play a paracrine role by secreting pro-angiogenic growth factors and cytokines (yellow triangles and blue squares) to stimulate vascular regeneration. Outgrowth endothelial cells (OECs; green) display a typical endothelial phenotype and have clinical potential for ischaemic disease as they home to ischaemic areas and directly integrate into denuded endothelium.